Effects of negative air ions treatment on the quality of fresh shiitake mushroom (Lentinus edodes) during storage

Fresh shiitake (Lentinus edodes) is prone to brown, pileus-opening and flavor-loss during storage. Therefore, it is important to find an effective preservation method for fresh shiitake. Negative air ions (NAI) are negatively-charged molecules or atoms in the air, and can affect the physiological metabolism of live cells and be conveniently used with low cost. In this study, NAI treatment was performed at different times and the physico-chemical characteristics, microstructure, membrane potential and energy metabolism of shiitake were determined during storage. Results showed that NAI treatment for 40 min could reduce 29% of browning index and maintain the hardness of shiitake. NAI treatment groups had higher content of sweetness amino acids, umami amino acids, 5'-IMP, eight-carbon alcohols compounds and cyclic sulfides compounds than the control, and comprehensive quality of the group being treated for 40 min was the best. The mitochondria of shiitake swelled and the membrane potential decreased after being treated by NAI. However, NAI treatment for 40 min could improve the contents of ATP and ADP, maintain a relatively stable energy charge level, and promote energy utilization of shiitake during storage. The results demonstrated that NAI treatment had the potential to improve the quality shiitake during storage.